In medical imaging of the thoracic cavity, intrafraction movement can have a significant effect on medical imaging quality. Intrafraction movement occurs when the patient and/or organs within the thoracic cavity (e.g., lungs, heart, etc.) move during an imaging scan. Respiratory movement, in particular, can have a significant affect on image quality and can produce a variety of artifacts (e.g., blur, distortion, etc.) within a medical image. These imaging artifacts can in turn affect the extent to which medical practitioners can rely on a medical image for diagnoses or for treatment planning. For example, in order to compensate for any uncertainties created by imaging artifacts, radiologists may need to over estimate a target treatment volume in a patient.
In general, there exist several techniques to account for respiratory motion in medical imaging. For example, these techniques can including breath-hold, respiratory gating or breathing coaching, which employs visual and/or audio feedback regarding when a patient should inhale and/or exhale. By controlling a patient's breathing in either of these manners, the amount of image artifacts can be reduced to an extent. Unfortunately, however, such breath-hold and coaching techniques are limited. For example, only about 40% of the lung cancer population can hold their breath for an adequate duration of time, and breathing coaching cannot account for irregular motion of the lungs (or irregular motion of tissues adjacent the lungs).